View source for Body surface area

In [[physiology]] and [[medicine]], the '''body surface area''' (BSA) is the measured or calculated surface of a [[human body]]. For many clinical purposes BSA is a better indicator of metabolic mass than body weight because it is less affected by abnormal adipose mass. Estimation of BSA is simpler than many measures of volume. 

==Uses==
Examples of uses of the BSA:
* [[Renal function|Renal clearance]] is usually divided by the BSA to gain an appreciation of the true required [[glomerular filtration rate]] (GFR);
* The [[Quetelet index]] uses a somewhat modified form of the BSA;
* The [[cardiac index]] is a measure of [[cardiac output]] divided by the BSA, giving a better approximation of the required cardiac output;
* [[Chemotherapy]] is often dosed according to the patient's BSA.
* [[Glucocorticoid]] dosing is also expressed in terms of BSA for calculating maintenance doses or to compare high dose use with maintenance requirement.

==Calculation==
Various calculations have been published to arrive at the BSA without direct measurement:

The Dubois & Dubois formula:<ref>Du Bois & Du Bois,''Arch Intern Med'' 1916, 17:863</ref>:

:<math>{BSA (m^2)}=0.007184 \times {weight \mbox{ (kg)}}^{0.425} \times {height \mbox{ (cm)}}^{0.725}</math>

or alternatively expressed:

:<math>{BSA (m^2)}=\frac{{weight \mbox{ (kg)}}^{0.425} \times {height \mbox{ (cm)}}^{0.725}}{139.2} </math>

One commonly used formula is the Mosteller formula, published in 1987<ref>Mosteller RD. "Simplified calculation of body-surface area". [[N Engl J Med]] 1987; 317:1098. PMID 3657876.</ref> and adopted for use by the Pharmacy and Therapeutics Committee of the Cross Cancer Institute, Edmonton, Alberta, Canada:

:<math>{BSA (m^2)}= \sqrt\frac{weight \mbox{ (kg)} \times height \mbox{ (cm)} }{3600}</math>

Other formulas include the Haycock formula<ref>Haycock GB, Schwartz GJ, Wisotsky DH "Geometric method for measuring body surface area: A height-weight formula validated in infants, children and adults" ''J Pediatr'' 1978, 93:62-66.</ref>:
:<math>{BSA (m^2)}=0.024265 \times {weight \mbox{ (kg)}}^{0.5378} \times {height \mbox{ (cm)}}^{0.3964}</math>

the Gehan and George formula<ref>Gehan EA, George SL, ''Cancer Chemother Rep'' 1970, 54:225-235</ref>:
:<math>{BSA (m^2)} = 0.0235 \times weight \mbox{ (kg)}^{0.51456} \times height \mbox{ (cm)}^{0.42246} </math>

the Boyd formula<ref>[http://www.ispub.com/journal/the_internet_journal_of_anesthesiology/volume_2_number_2_55/article/a_linear_equation_for_estimating_the_body_surface_area_in_infants_and_children.html "(from Boyd E, The growth of the surface area of the human body." ] Minneapolis: University of Minnesota Press, 1935.)</ref>:
:<math>{BSA (m^2)} = 0.0003207
 \times weight \mbox{ (g)}^{(0.7285 - 0.0188 \log_{10}{weight \mathrm{ (g)}})}
 \times height \mbox{ (cm)}^{0.3}</math>

the Fujimoto formula<ref>Fujimoto S, Watanabe T, Sakamoto A, Yukawa K, Morimoto K. Studies on the physical surface area of Japanese. 18. Calculation formulae in three stages over all ages. Nippon Eiseigaku Zasshi 1968;5:443–50.</ref>
:<math>{BSA (m^2)} = 0.008883 \times height \mbox{ (cm)}^{0.663} \times weight \mbox{ (kg)}^{0.444}</math>

the Takahira Formula <ref>Fujimoto S, Watanabe T, Sakamoto A, Yukawa K, Morimoto K. Studies on the physical surface area of Japanese. 18. Calculation formulae in three stages over all ages. Nippon Eiseigaku Zasshi 1968;5:443–50.</ref>

:<math>{BSA (m^2)} = 0.007241 \times height \mbox{ (cm)}^{0.725} \times weight \mbox{ (kg)}^{0.425}</math>

==Normal values==
"Normal" BSA is generally taken to be 1.73 m² for an adult.

:{|
! colspan="3" | Average BSA values
|-
| Neonate (Newborn) || 0.25 ||m²
|-
| Child 2 years ||  0.5 || m²
|-
| Child 9 years || 1.07 || m²
|-
| Child 10 years || 1.14 || m²
|-
| Child 12-13 years || 1.33 || m²
|-
|For men   || 1.9 || m²
|-
|For women || 1.6 || m²
|}

==References==
<div class="references-small">
<references/>
</div>

==External links==
* [http://www.bccancer.bc.ca/HPI/drugdatabase/appendices/appendix9.htm BC Cancer network] BSA calculation guidelines.
* [http://www.cato.eu/body-surface-area.html Online Body Surface Area Calculator (Dubois Formula)]
* [http://www.cato.eu/body-surface-area-children-1.html Online Body Surface Area Calculator (Mosteller Formula)]
* [http://www.webcooltools.com/Medicine/BSA.html Web CoolTool to Calculate BSA using any of the five formulae]

[[Category:Pharmacology]]

[[de:Körperoberfläche]]
[[es:Área de superficie corporal]]
[[fr:Surface corporelle]]
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[[pl:Powierzchnia ciała]]
[[ru:Площадь поверхности тела]]
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